Page 46 - Shawl Weaving Artisan - TT

10 Temples 2 Picking (Weft insertion)
• Function: Devices located at the selvedges • Theory: This is the process of inserting the weft
(edges) of the fabric that hold the cloth taut and thread through the newly formed shed.
at a consistent width, preventing it from narrowing • Mechanism
due to the tension of weaving.
- Shuttle Looms: The shuttle, containing the pirn
11 Take-up roller (or cloth roller) of weft yarn, is propelled across the shed by a
• Function: Located at the front of the loom, this picking mechanism (e.g., using picking sticks
roller winds up the woven fabric as it is produced. and an eccentrically rotating picking cam). As
12 Let-off motion the shuttle travels, the weft yarn unwinds from
the pirn.
• Function: Controls the unwinding of the warp • Shuttleless looms
yarn from the warp beam at a precise rate and
maintains consistent tension on the warp threads. - Rapier: A rapier head enters the shed from
one side, grips the weft yarn, and carries it to
13 Stop motions (Warp stop motion, weft stop
motion) the center, where a second rapier head takes
it and carries it to the other side.
• Function: Safety mechanisms that automatically - Projectile: A small projectile is fired across the
stop the loom if a warp thread breaks or if the weft shed, carrying a clamp that holds the weft yarn.
yarn runs out or breaks. This prevents defects in
the fabric and allows for quick intervention. - Air-jet/water-jet: A precisely timed blast of air
The operation of a power loom, regardless of its or water propels the weft yarn through the shed.
These methods are extremely fast.
specific type (shuttle or shuttleless), revolves around
the sequential execution of three primary motions and 3 Battening (Beating-up)
several secondary and auxiliary motions. These motions • Theory: After the weft thread is inserted, it needs
are precisely synchronized to interlace the warp and weft to be pushed firmly into the “fell of the cloth” (the
yarns, forming fabric. point where the previously woven fabric ends) to

Primary motions of weaving create a compact and stable fabric.
The three fundamental motions that must occur in every • Mechanism: The reed, mounted on a sley or
cycle of weaving are: batten, swings forward and strikes the newly
inserted weft thread, pushing it into place. This
1 Shedding motion is precisely timed to occur after the weft

• Theory: This is the process of dividing the warp insertion is complete and the shed is closed or
threads into two layers to form an opening called partially closed.
the “shed.” This opening allows for the passage Secondary motions of weaving
of the weft insertion device. These motions ensure continuous and smooth weaving:
• Mechanism: It is achieved by raising some warp 1 Take-up motion
threads and lowering others. The specific pattern
of raised and lowered threads determines the • Theory: As fabric is woven, it must be wound onto
weave structure (e.g., plain weave, twill weave, the cloth roller at a controlled and constant rate
satin weave). This lifting and lowering is controlled to maintain uniform fabric density and allow for
by the harnesses and the shedding mechanism continuous weaving.
(tappet, dobby, or jacquard). • Mechanism: This motion involves a series of

• Types of sheds gears and rollers that pull the woven fabric from
the weaving area and wind it onto the cloth roller.
- Bottom closed shed: All warp threads start The speed of the take-up motion is critical for
at the same level. Some are lifted to form the determining the picks per inch (PPI) of the fabric.
shed, and then all return to the bottom before 2 Let-off motion
a new shed is formed.
• Theory: This motion controls the unwinding of the
- Center closed shed: Warp threads move from warp sheet from the warp beam, supplying fresh
a center position, either up or down, to form the warp yarns to the weaving area at the required
shed, and then return to the center. rate and under precise tension.
- Open shed: Warp threads, once raised or • Mechanism: Can be positive (driven by gears,
lowered, remain in their respective positions common in modern looms) or negative (controlled
until they need to change for the next pick. This by friction or weight, less common in high-speed
is the most common for high-speed looms as looms). Maintaining correct warp tension is crucial
it reduces strain on the yarns and wear on the to prevent warp thread breakages and ensure
shedding mechanism. fabric quality.

36 Textile & Handloom: Shawl Weaving Artisan : (NSQF - 2024) R.T. Ex.No 1.3.26